Plantation | EPFL Graph Search

thumb|Une plantation d'hévéa en Malaisie.Une plantation est une exploitation agricole où l'on cultive des plantes à forte valeur économique destinées principalement à la vente sur les marchés internationaux. Ces cultures sont, par exemple, les agrumes, l'avocatier, le coton, la canne à sucre, le café, la banane, l'ananas, lAloe vera, le teck, le cacao, la coca, le chanvre, le pavot, l'hévéa, le sisal, l'indigotier, le giroflier, le cocotier, le palmier à huile, le poivre, le thé, le tabac, les fleurs ou la vanille. Historiquement on employait le terme plantation pour désigner .vignette|Affiche de propagande coloniale belge faisant allusion aux plantations, années 1920. L'agriculture de plantation privilégie la monoculture de plantes tropicales pluriannuelles destinées aux grands marchés et fait appel à une main-d'œuvre à bas-salaire (à l'esclavage autrefois) mais ce n'est pas une règle. Elle implique un contrôle accentué sur les terres mises en culture et si besoin sur leur approvisio

Reclamation of low fertility soils using by-products and fast-growing trees

Marc Adami

The world population being increasing, a good energy production management is therefore necessary. Biomass production through short forest rotation by using fast-growing trees appears as a sensible way to limit fossil fuel uses. In Mediterranean regions of south-east Spain, soils present weakened ecosystem with low organic matter and nutrients content which are prone to irremediable degradation processes. The very low fertility of those soils usually makes them unfit to food production and so tree plantation with amendment addition seems to be a possible solution in order to use those soil and improve their qualities. In this study, a low fertility soil was exposed to the addition of two types of amendment (a compost of “Alperujo” and one of biosolid) and to the plantation of two different fast-growing trees (poplars and eucalyptus) during a time period of four months. The soil quality was determined by measuring different selected biochemical (β-glucosidase, phosphatase, dehydrogenase and urease activities), chemical (pH, electrical conductivity, organic matter, phosphate, potassium, water-soluble carbon, N-Kjeldahl, permanganate oxidizable carbon and metal extractible with CaCl2) and plants (nutrients, and trace elements) parameters. No significant differences between the different conditions were found. This was due to the very short time period, the too small doses of compost additions and the very high spatial variability due to the field conditions. It seems however that the composts had a positive effect on the chemical and biochemical parameters in the plots planted with poplars as the results presented systematically higher values for the amended plots than for the control plots (without amendment addition). This was attributed to the fact that all poplars were dead at the time of the study and so the soil was not confronted to any interference by the rhizosphere. Most of the parameters (chemical as well as biochemical) of the soil were improved in the eucalyptus plots compared to the poplar ones. This suggests the stimulation of the nutrient cycles by the tree roots, which improved the conditions for the microorganisms, increasing therefore their metabolic activities. The effect of composts in the eucalyptus plots were therefore clearly less obvious, probably due to the fact that the rhizosphere have had more time (tree planted in July 2011) to influence the soil properties than the compost (added in November 2011). Although both composts contained a non negligible quantity of micronutrients and trace elements, the extractible by CaCl2 0.01M quantities in soil (representing the available quantity for plants) did not present values too high to be toxic for plants and were all in normal ranges. The biomass development of the trees seems to have been improved by the compost of “Alperujo”, but presented a very high spatial variability. The compost of biosolids for its part did not show any difference as compared to the control. Next studies should reveal more significant differences between the plots, the soil having more time to react to the new conditions. It is however recommended to increase the addition doses of composts (double or more) in order to show better their effects

2012

Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

Thomas Guillaume

Tropical forest conversion to agricultural land leads to a strong decrease of soil organic carbon (SOC) stocks. While the decrease of the soil C sequestration function is easy to measure, the impacts of SOC losses on soil fertility remain unclear. Especially the assessment of the sensitivity of other fertility indicators as related to ecosystem services suffers from a lack of clear methodology. We developed a new approach to assess the sensitivity of soil fertility indicators and tested it on biological and chemical soil properties affected by rainforest conversion to plantations. The approach is based on (non-)linear regressions between SOC losses and fertility indicators normalized to their level in a natural ecosystem. Biotic indicators (basal respiration, microbial biomass, acid phosphatase), labile SOC pools (dissolved organic carbon and light fraction) and nutrients (total N and available P) were measured in Ah horizons from rainforests, jungle rubber, rubber (Hevea brasiliensis) and oil palm (Elaeis guineensis) plantations located on Sumatra. The negative impact of land-use changes on all measured indicators increased in the following sequence: forest < jungle rubber < rubber < oil palm. The basal respiration, microbial biomass and nutrients were resistant to SOC losses, whereas the light fraction was lost stronger than SOC. Microbial C use efficiency was independent on land use. The resistance of C availability for microorganisms to SOC losses suggests that a decrease of SOC quality was partly compensated by litter input and a relative enrichment by nutrients. However, the relationship between the basal respiration and SOC was non-linear; i.e. negative impact on microbial activity strongly increased with SOC losses. Therefore, a small decrease of C content under oil palm compared to rubber plantations yielded a strong drop in microbial activity. Consequently, management practices mitigating SOC losses in oil palm plantations would strongly increase soil fertility and ecosystem stability. We conclude that the new approach enables quantitatively assessing the sensitivity and resistance of diverse soil functions to land-use changes and can thus be used to assess resilience of agroecosystems with various use intensities. (C) 2016 Elsevier Ltd. All rights reserved.

Elsevier Science Bv2016

Effects of flooding on phosphorus and iron mobilization in highly weathered soils under different land-use types: Short-term effects and mechanisms

Thomas Guillaume

The strong affinity of phosphorus (P) to iron (Fe) oxides and hydroxides in highly weathered tropical soils limits P availability and therefore plant productivity in tropics. In flooded soils, however, P fixed by Fe oxides and hydroxides can be released into more available forms because of Fe3+ reduction to Fe2+. These P dynamics in flooded soils are well documented for rice paddies. Such effects are much less studied in other land-use types influenced by seasonal flooding, especially in the tropics during heavy monsoon rains. The aim of this study was to investigate the P mobilization during flooding leading to anaerobic conditions in topsoil and subsoil depending on land-use type. Samples were collected in highly weathered Acrisols from four replicate sites under natural rainforest, jungle rubber, rubber and oil palm plantations in Sumatra, Indonesia. Topsoil and subsoil were taken to ensure a wide range of soil organic matter (SOM) and P contents. Soils were incubated under anaerobic, flooded conditions at 30 +/- 1 degrees C for 60 days, Our results confirmed the hypothesis that soil flooding mobilizes P and increases P availability. Two distinct and opposite periods were observed during the flooding. During the first three weeks of flooding, the dissolved P (DP) concentration peaked, simultaneously with the peak of dissolved Fe2+ (DFe2+) and dissolved organic carbon (DOC). After three weeks, P availability in soils decreased, although Fe-P (P-NaOH) and available P (P-NaHCO3) did not reach the initial, pre-flooding levels. The impacts of flooding on P and Fe forms was strong in the topsoil, where P dissolution and availability were generally higher under forest and, to a lesser extent, under jungle rubber. A positive correlation between DOC and DFe2+ (R-2 = 0.42) in topsoil indicates that the intensity of microbially-mediated Fe3+ reduction is limited by the amount of available carbon (C) as an energy source for microorganisms and as electron donor. Microbial mineralization of organic P from SOM also increases P availability, and this process requires available C. This interpretation was supported by the strong correlation (R-2 = 0.58) between available P and DOC, as well as between DP and DOC (R-2 = 0.56) in topsoil. The increasing pH in topsoil and subsoil after flooding of all land use types may also influence the P release over time. In summary, the increase of available P and DP during flooding is due to three main mechanisms: (1) P release via the microbially-mediated reductive dissolution of Fe3+ oxides; (2) P release during SOM mineralization and (3) solubility of Fe phosphate due to increasing pH. These mechanisms are relevant not only in riparian areas, where flooding occurs, but also in soils waterlogged after regular heavy rainfalls during the wet season. Therefore, we speculate that the P turnover is faster in compacted soils under plantations because of regular changes of oxic and anoxic conditions. Consequently, more P is pumped by the vegetation and then removed from plantatioris due to yield export.

Elsevier Science Bv2017

Reclamation of low fertility soils using by-products and fast-growing trees

Marc Adami

2012

Sensitivity and resistance of soil fertility indicators to land-use changes: New concept and examples from conversion of Indonesian rainforest to plantations

Thomas Guillaume

Elsevier Science Bv2016

Effects of flooding on phosphorus and iron mobilization in highly weathered soils under different land-use types: Short-term effects and mechanisms

Thomas Guillaume

Elsevier Science Bv2017